Fix Type#cast to support Rails 8.0 bulk operations

[snaka]

Important

To run tests on this PR, it is necessary to merge the following PRs first

• Update GitHub Actions runner to ubuntu-24.04 #466

Motivation / Background

This Pull Request has been created because Rails 8.0 introduced changes to how Type#cast is used during bulk operations (insert_all, upsert_all), causing enumerated attributes with symbol values to fail. The issue affects only bulk operations while regular attribute assignment continues to work correctly.

Fixes #462

Detail

This Pull Request changes the Type#cast method in enumerize to handle values more intelligently for Rails 8.0 compatibility.

Steps to reproduce

class User < ActiveRecord::Base
  enumerize :status, in: { active: 1, inactive: 0 }
end

# This works in Rails 7.x but fails in Rails 8.0
User.insert_all([{ status: :active }])
User.upsert_all([{ status: :active }])

Expected behavior

Bulk operations (insert_all, upsert_all) should work correctly with symbol enum values like :active, just like regular attribute assignment does.

Actual behavior

In Rails 8.0, bulk operations fail when using symbol enum values because the Type#cast method incorrectly delegates to @subtype.cast first, which returns nil for symbols when the subtype is an integer type.

System configuration

Rails version: 8.0

Ruby version: 3.1.6

Testing

Added comprehensive tests for:

• Type#cast behavior with symbols, strings, and integers
• insert_all with mixed value types
• upsert_all with different value formats
• Handling of invalid enum values
• Preservation of existing Enumerize::Value objects

All tests pass on Rails 7.0, 7.1, and 8.0.